The invention relates to the field of the furniture industry. It involves a chair with adjustable seat depth.
Different technical solutions for chairs are known, with which the seat depth of the chair can be adjusted to the respective user""s leg length.
For example in the Chicago model revealed by the applicant the entire seat can be moved forward (or back) on a rail. The disadvantage of this system is that the entire seat trough, the front over arch for the support of the thighs as well as the support for the iliac crest move forward and thus the distance to the backrest support point increases. This way optimal sitting is no longer possible.
We also know of a chair from Sitag company with a seat that is divided into two parts, where one part of the seat slides beneath the other part and thus a seat depth adjustment occurs. This technical solution has the disadvantage that the cushion is separated in the front area and thus no continuous surface exists. This leads to an unpleasant sitting experience for the user. Additionally pressure points can arise during sitting.
Finally we know from the magazine Office Design from Jun. 3, 2000, p. 65 of an office chair with a sliding seat, where the cushion plate of the chair is pulled over a wedge for iliac crest support. The iliac crest support should always remain in a fixed position to the back when changing the seat depth. Although new cushion technology, where the cushion foam in the marginal areas and in the areas of the legs is firmer than in the area on which the thighs rest, ensures high sitting comfort, this comfort however is reduced again disadvantageously due to the lacking seat trough.
The invention attempts to avoid the above-mentioned disadvantage of the familiar state of the art. Its objective is to create a chair with adjustable seat depth, where the seat depth can be adjusted without difficulty to the different lengths of users"" legs and where the seat trough always remains in the same position so that extremely high sitting comfort is guaranteed.
According to the invention this is accomplished with a chair pursuant to the generic description of patent claim 1 in that the seat cushion plate contains a flexible area, which forms a seat trough, that on the seat support plate two lateral side rails are arranged, in which the seat cushion plate can be displaced through guide ribs that are incorporated in this plate, and that between the seat support plate and the seat cushion plate a device for improving the sliding characteristics is arranged.
The advantages of the invention are that with the invented sliding seat the seat trough for the user remains in the optimal position and that the seat depth can be exactly adjusted to the length of the respective user""s legs. Solely the movement of the user leads to a deformation of the seat cushion plate. This way excellent sitting comfort is achieved.
It is useful when at least three guide ribs are provided on the seat cushion plate for each lateral guide track of the seat support plate. This zipper principle leads to exact contour guidance. Although the seat cushion plate largely matches the outline of the seat support plate from a design point of view, it is not congruent with it but rather bent downward by a certain degree so that a an arch created. The parts are therefore mounted under tension.
Furthermore it is beneficial when the device for improving the sliding properties is a foil, which consists of polyethylene and is coated with Teflon and which is fastened to the seat support plate through a clamp. The seat cushion plate can then glide particularly well on the seat support plate so that the seat depth can be adjusted very easily and in a user-friendly manner.
It is advantageous when the seat cushion plate consists of ductile resin, which is particularly ductile in the flexible area due to a special interrupted outline.
Furthermore it is useful when the seat cushion plate can be fastened with the help of sliding blocks that are screwed into the fastening domes of the seat support plate and the sliding blocks form a stop to the front and/or the back for displacement of the seat cushion plate.
It is beneficial when on the seat support plate a arresting button is provided for a graduated arresting of the seat cushion plate. This way the seat depth can be adjusted exactly to the respective needs and be locked in place.
Finally it is useful when the seat cushion plate contains a maximum displacement area of about 60 mm.